Apparatus for interworking between heterogeneous No.7 signaling networks and method thereof

ABSTRACT

The present invention relates to a common channel signaling network, and more particularly, to an apparatus and method for interworking between heterogeneous No. signaling networks. Additional functions required for interworking between erogeneous No.  7  signaling networks can be minimized by operating the function of naging a signaling network and the function of handling a signaling message, pectively, during interworking between different No. 7 signaling networks. In ition, the reliability and performance of a signaling network can be maximized by ng an already established function of managing each signaling network.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a common channel signalingnetwork, and more particularly, to an apparatus for interworking betweenheterogeneous No. 7 signaling networks and method thereof.

[0003] 2. Background of the Related Art

[0004] Generally, common channel signaling (CCS) is a signaling methodin which traffic lines and signaling lines are operated. Signals forcalls are transmitted via the signaling lines. A No. 7 signaling networkis one common channel signaling method.

[0005] Since a No. 7 signaling network is configured according to thethen current recommendation to the ITU-T, or by different providers,heterogeneous No. 7 signaling networks exist.

[0006]FIG. 1 is a drawing illustrating the relationship betweenheterogeneous No. 7 signaling networks. As illustrated in FIG. 1,signaling point C carries out interconnection between signaling networkx and signaling network y, which are different from each other.

[0007] Signaling point C executes a signaling network managementfunction of appropriately reconstructing a signaling network in order toensure a reliable transmission of a signaling message, according to therequirements for signaling network performance even when a signalinglink and a signal transfer point are in an abnormal state. Signalingpoint C further provides a signaling message handling function ofreliably transferring a signaling message generated by a user part of anoriginating signaling point to a target user part of a destinationsignaling point.

[0008] Signaling point C integrally manages signaling networks,regardless of the types of signaling networks. Thus, a signaling networkmanagement that conforms to the characteristics of the correspondingsignaling network is performed by judging a signaling network to whichthe destination signaling point of the corresponding signaling messagebelongs whenever the corresponding signaling message is discriminated.In addition, since signaling network x and signaling network y areseparate signaling networks, signaling point C performs the screeningfunction of a signaling network management message.

[0009] Referring to FIG. 2, signaling point C includes a messagediscrimination unit 1, a message distribution unit 2, and a messagerouting unit 3, so as to perform the signaling message handlingfunction. The message discrimination unit 1 determines whether or notthe destination signaling point of a signaling message is a signalingpoint to which the message discrimination unit 1 belongs. If thedestination signaling point is a signaling point to which the messagediscrimination unit 1 belongs, the message distribution unit 2distributes the signaling message to the corresponding local user part.If not, the message routing unit 3 routes the signaling message to anultimate destination signaling point.

[0010] The related art interworking between heterogeneous No. 7signaling networks has various problems. For example, signaling networksmust be separated from each other in view of the management of signalingnetworks since the interworking between the networks means theinterworking between signaling messages. However, because a signalingpoint for interworking between heterogeneous No. 7 signaling networks inthe related art integrally carries out the signaling network managementfunction regardless of the types of signaling networks, each signalingnetwork must perform the additional function of screening a signalingnetwork management message of other signaling networks.

[0011] In addition, since the signaling point for interworking betweenheterogeneous No. 7 signaling networks in the related art carries outthe signaling message handling function regardless of the types ofsignaling networks, the signaling network to which the destinationsignaling point of the corresponding signaling message belongs must bejudged whenever the corresponding signaling message is discriminated,thus increasing the load of the signaling point.

[0012] Moreover, when another interworking between signaling networks isnecessary, the existing software for executing the signaling networkmanagement function cannot be reused, but instead requires an overallmodification. Consequently, a lot of time and cost is needed forfunctional stabilization.

[0013] The above references are incorporated by reference herein whereappropriate for appropriate teachings of additional or alternativedetails, features and/or technical background.

SUMMARY OF THE INVENTION

[0014] An object of the invention is to solve at least the aboveproblems and/or disadvantages and to provide at least the advantagesdescribed hereinafter.

[0015] It is another object of the present invention to provide a methodand apparatus for interworking between heterogeneous No. 7 signalingnetworks that is capable of efficiently routing a signaling message toother signaling networks by executing a signaling network managementfunction and a signaling message handling function, respectively,according to the type of a signaling network during interworking betweendifferent No. 7 signaling networks.

[0016] To achieve at least the above objects in whole or in parts, thereis provided an apparatus for interworking between heterogeneous No. 7signaling networks according to the present invention, which includes aplurality of signaling network processing units corresponding toheterogeneous No. 7 signaling networks to interwork with each other oneto one and executing a signaling network management function andsignaling message handling function for a corresponding signalingnetwork respectively, and a cross-routing controlling unit disposedbetween the plurality of signaling network processing units for storingnetwork management information of each signaling network transmittedfrom the plurality of signaling network processing units andcross-routing a signaling message between the plurality of signalingnetwork processing units based on the stored network managementinformation of each signaling network.

[0017] To further achieve at least the above objects in whole or inparts, there is provided a method of interworking between heterogeneousNo. 7 signaling networks according to the present invention, whichincludes managing the status information of signaling networks belongingto each signaling network by receiving status information of signalingpoints belonging to each signaling network from signaling networkprocessing units separated according to the type of a signaling network,and requesting cross-routing of a received signaling message toheterogeneous signaling networks, if the destination signaling point ofthe signaling message is not contained in homogeneous networks; andcross-routing the signaling message to the signaling network belongingto the destination signaling point, if it is judged that cross-routingis possible based on the status of the destination signaling point ofthe signaling message to be requested to be cross-routed and thereceived status information of signaling points.

[0018] Additional advantages, objects, and features of the inventionwill be set forth in part in the description which follows and in partwill become apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objects and advantages of the invention may be realizedand attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

[0020]FIG. 1 is a block diagram illustrating one example of theinterconnection relationship between heterogeneous No. 7 signalingnetworks;

[0021]FIG. 2 is a block diagram illustrating blocks for handling amessage of an apparatus for interworking between heterogeneous No. 7signaling networks according to the related art;

[0022]FIG. 3 is a block diagram illustrating interworking betweenheterogeneous No. 7 signaling networks according to a preferredembodiment of the present invention;

[0023]FIG. 4 is a drawing illustrating a protocol structure for asignaling point for carrying out interworking between heterogenous No. 7signaling networks according to the preferred embodiment of the presentinvention;

[0024]FIG. 5 is a block diagram illustrating a signaling messagehandling unit of each signaling network processing unit in the apparatus(signaling point) for carrying out interworking between heterogeneousNo. 7 signaling networks according to the preferred embodiment of thepresent invention;

[0025]FIG. 6 is a flow chart illustrating a signaling network managementmethod in the apparatus for interworking between heterogeneous No. 7signaling networks according to the preferred embodiment of the presentinvention;

[0026]FIG. 7 is a flow chart illustrating a method of requestingcross-routing of a signaling message in the apparatus for interworkingbetween heterogeneous No. 7 signaling networks according to thepreferred embodiment of the present invention; and

[0027]FIG. 8 is a flow chart illustrating a method of cross-routing asignaling message in the apparatus for interworking betweenheterogeneous No. 7 signaling networks according to the preferredembodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0028] The preferred embodiment of the present invention will now bedescribed with reference to the accompanying drawings.

[0029] The apparatus for interworking between heterogeneous No. 7signaling networks and method thereof according to the present inventionis identical to that shown in FIG. 1. Accordingly, no additionaldescription will be given.

[0030]FIG. 3 is a block diagram illustrating the interworking betweenheterogeneous No. 7 signaling networks according to the preferredembodiment.

[0031] As illustrated in FIG. 3, the apparatus for interworking betweenheterogeneous No. 7 signaling networks preferably includes a signalingnetwork x processing unit 10 for interfacing with signaling network x, asignaling network y processing unit 20 for interfacing with signalingnetwork y, and a cross-routing controlling unit 30 coupled between thesignaling network x processing unit 10 and the signaling network yprocessing unit 20. The cross-routing control unit 30 is configured toperform cross-routing of a signaling message between heterogeneoussignaling networks x and y.

[0032] The signaling network x processing unit 10 and the signalingnetwork y processing unit 20 each preferably include a signaling networkmanagement unit 13 and 23 for performing network management of acorresponding signaling network and transmitting the state of eachsignaling point corresponding to the signaling network to thecross-routing controlling unit 30. Each signaling network processingunit 10, 20 further includes a signaling message handling unit 15 and25, to transmit the signaling message to be cross-routed toheterogeneous signaling networks from the signaling messages transmittedfrom the corresponding signaling network to the cross-routingcontrolling unit 30, and route the signaling message transmitted fromthe cross-routing controlling unit 30 to the corresponding signalingnetwork.

[0033] The cross-routing controlling unit 30 preferably cross-routes asignaling message to the signaling network processing unit in thesignaling network to which the destination signaling point of thesignaling message belongs. This is done by referring to a signalingpoint status information transmitted from each signaling networkprocessing unit 10 and 20.

[0034]FIG. 4 illustrates a protocol structure for a signaling point forcarrying out interworking between heterogeneous No. 7 signaling networksaccording to the preferred embodiment. As shown therein, the protocolstack of the signaling point for carrying out interworking betweenheterogeneous No. 7 signaling networks preferably includes a messagetransfer part (MTP) 100, for performing the transfer of a signalingmessage and a cross-routing controlling part 110, for performinginterworking of a signaling message between heterogeneous No. 7signaling networks. The protocol stack further includes a telephone userpart (TUP) 120, for performing functions such as telephone signalprocessing, call switched connection control, etc., and an ISDN userpart (ISUP) 130, for handling a wide variety of services of anIntegrated Services Digital Network (ISDN). Finally, the protocol stackincludes a signaling connection control part (SCCP) 140, for enablingthe transmission of various signals or data besides commonline-associated control signals, and a transaction capabilities (TC)part 150, for performing control of a conversion facility and specialcenters (e.g., a database, special facility unit, and maintenance &repair center).

[0035] The TUP 120, ISUP 130, and SCCP 140 are MTP user parts, and theTC 5 is a SCCP user part. Particularly, the cross-routing controllingpart 110 added according to the present invention is recognized as a MTPuser part by the MTP 100.

[0036] In comparison of the MTP 100 with the OSI (Open SystemInterconnection) model of the ISO (International Organization forStandardization), MTP level 1 executes the functions of layer 1 of theOSI, MTP level 2 executes the functions of layer 2 of the OSI, and MTPlevel 3 executes the functions of layer 3 of the OSI.

[0037] In addition, the signaling network x processing unit 10 and thesignaling network y processing unit 20, as shown in FIG. 3, execute theMTP protocol function of FIG. 4, and the cross-routing controlling unit30 is recognized as a MTP user part for a MTP protocol element.

[0038] Therefore, the signaling network processing unit performing theMTP protocol function of the present invention interfaces with acorresponding signaling network in a one-to-one manner, and thecross-routing controlling unit performing the MTP user part functioncross-routes a signaling message between the signaling networkprocessing units.

[0039]FIG. 5 is a diagram illustrating the signaling message handlingunit 15, 25 of each signaling network processing unit in the apparatus(signaling point) for carrying out interworking between heterogeneousNo. 7 signaling networks according to the preferred embodiment.

[0040] As illustrated in FIG. 5, the signaling message handling unit 15,25 of each signaling network processing unit 10, 20 preferably includesa message discrimination unit 15 a, 25 a for determining whether or notthe destination signaling point of the signaling message transmittedfrom a corresponding signaling network is a current signaling point.Each unit 10, 20 further includes a message distribution unit 15 b, 25b, for distributing the signaling message to a local MTP user part, ifthe destination signaling point of the signaling message is the currentsignaling point, and a message routing part 15 c, 25 c, for requestingthat the signaling message be cross-routed to a heterogeneous signalingnetwork, if the destination signaling point of the signaling message isnot the current signaling point and does not exist in the correspondingsignaling network.

[0041] In operation, each signaling network management unit 13, 23 ofeach signaling network processing unit 10, 20 transmits statusinformation for each signaling point contained in a correspondingsignaling network that interfaces with the signaling network managementunit 13, 23 to the cross-routing controlling unit 30. The cross-routingcontrolling unit 30 stores the status information of each signalingpoint received from the corresponding signaling network management unit13, 23 and manages the status of each signaling point of heterogeneoussignaling networks.

[0042] If a signaling message is to be transmitted from a signalingnetwork, the corresponding signaling message handling unit 15, 25transmits the signaling message to the cross-routing controlling unit 30so that the destination signaling point of the received signalingmessage is cross-routed to heterogeneous signaling networks if thereceived signaling message's destination does not exist in the signalingpoint, i.e., it does not exist in homogeneous signaling networks. Thecross-routing controlling unit 30 cross-routes the signaling message tothe destination signaling network processing unit in accordance with thestatus information of each signaling point. The destination signalingmessage handling unit receives the signaling message from thecross-routing controlling unit, and routes the received signalingmessage to the corresponding destination signaling point.

[0043] The operation of the apparatus for interworking betweenheterogeneous No. 7 signaling networks according to the preferredembodiment will now be described in more detail with reference to theaccompanying drawings.

[0044] Referring to FIG. 6, the signaling network management unit 13 ofthe signaling network x processing unit 10 transmits a MTP primitive tothe cross-routing controlling unit 30. The MTP primitive represents thestatus information of the signaling point contained in signaling pointx. In addition, the signaling network management unit 23 of thesignaling network y processing unit 20 also transmits a MTP primitiverepresenting the status information of the signaling point contained insignaling point y to the cross-routing controlling unit 30. These MTPprimitives are received by the crossrouting control part in step S110.

[0045] The cross-routing controlling unit 30 then checks the type of thereceived MTP primitive to determine if the primitive is a MTP-RESUMEprimitive in step S120. If the received MTP primitive is a MTP-RESUMEprimitive, then a signaling message can be transferred to thecorresponding signaling point. Accordingly, the cross-routingcontrolling unit 30 indicates the status of the signaling point of thecorresponding signaling network as “accessible” in a database managingthe status of a signaling point of each signaling network in step S130.

[0046] If the primitive is not a MTP-RESUME primitive, then it isdetermined if it is a MTP-PAUSE primitive in step S140. If the primitiveis a MTP-PAUSE primitive, indicating that a signaling message cannot betransferred to the corresponding signaling point, the cross-routingcontrolling unit 30 indicates the status of the signaling point as“inaccessible” in the database in step S150.

[0047] If the primitive is not a MTP-PAUSE primitive, then it isdetermined if it is a MTP-CONGESTION primitive in step S160. If thereceived MTP primitive is a MTP-CONGESTION primitive, indicating that acorresponding signaling point is congested, the cross-routingcontrolling unit 30 indicates the status of the signaling point as“congestion” in step S170.

[0048] The cross-routing controlling unit 30 thus manages the status ofeach signaling point of heterogeneous signaling networks.

[0049] Referring next to FIG. 7, a method of requesting cross-routing ofa signaling message is described. The signaling message handling unit 15of the signaling network x processing unit 10 initially receives asignaling message from signaling network x. If the messagediscrimination unit 15 a of the signaling message handling unit 15transmits a request for routing the signaling message, the request isreceived by the message routing unit 15c in step S210. Next, the messagerouting unit 15 c determines whether the destination signaling pointexists in signaling network x, in step S215.

[0050] If the destination signaling point exists in signaling network x,it is next determined whether the destination signaling point isaccessible or inaccessible in step S220. If accessible, the signalingmessage is routed to the destination signaling point of signalingnetwork x, in step S225. If, however, the destination signaling point isinaccessible, the message routing unit 15 c discards the signalingmessage in step S230, and prohibits the transfer of a signaling messageto the destination signaling point in step S235.

[0051] If in step S215 it is determined that the destination signalingpoint does not exist in signaling network x, the message routing unit 15c determines whether the cross-routing of the signaling message ispossible or impossible in step S240.

[0052] To make this determination, the message routing unit 15 c storesinformation regarding signaling points of each signaling network capableof cross-routing a signaling message between heterogeneous signalingnetworks. If the destination signaling point of a signaling messagecorresponds to one of the stored signaling points, it is determined thatthe cross-routing of the corresponding signaling message is possible.If, however, the destination signaling point does not correspond to oneof the stored signaling points, it is determined that the cross-routingof the corresponding signaling message is impossible.

[0053] Therefore, in step S240, the message routing unit 15c determineswhether the destination signaling point of the signaling messagecorresponds to one of the signaling points capable of cross-routing. Ifthe destination signaling point corresponds to one of the signalingpoints capable of cross-routing, the message routing unit 15 cdetermines that the cross-routing of the signaling message is possible,and transmits the signaling message to the cross-routing controllingunit 30 using a MTP-TRANSFER indication primitive in step S245.

[0054] If, however, the destination signaling point does not correspondto one of the signaling points capable of cross-routing, the messagerouting unit 15 c determines that the cross-routing of the signalingmessage is impossible, and discards the signaling message in step S230.Then, the procedure of prohibiting the transfer of the signaling messageto the destination signaling point is performed in step S235.

[0055] Meanwhile, if the signaling message is cross-routed from thecross-routing controlling unit 30 via the MTP-TRANSFER request primitiveand received by the message routing unit in step S210, the messagerouting unit 15 c determines whether the destination signaling point ofthe cross-routed signaling message is contained in a correspondinghomogeneous signaling network, as shown in step S215. If so contained,it is then determined whether the destination signaling point isaccessible in step S220. If the destination signaling point isdetermined to be accessible, the message routing unit 15 c routes thesignaling message to the corresponding destination signaling point instep S225.

[0056] It should be noted that the operation of the signaling messagehandling unit 25 of the signaling network y processing unit 20 iscarried out in the same manner as the operation of the signaling messagehandling unit 15 of the signaling network x processing unit 10.

[0057] Referring next to FIG. 8, a method of cross-routing a signalingmessage is described. When the cross-routing controlling unit 30receives a MTP-TRANSFER indication primitive from the signaling messagerouting unit 15 c of the signaling message handling unit 15 in stepS250, the cross-routing controlling unit 30 determines whether thedestination signaling point of the signaling message to be cross-routedexists, as shown in step S255. The cross-routing controlling unit 30preferably stores information relating to signaling points capable ofcross-routing for each signaling network, and manages the same. Thus, itis determined whether the destination signaling point of the signalingmessage to be cross-routed corresponds to ones of the signaling pointscapable of cross-routing.

[0058] As a result of the determination in step S255, if it is possibleto cross-route the signaling message to the destination signaling point,it is then determined whether the destination signaling point of thesignaling message to be cross-routed is accessible in step S270. Thisdetermination is made based on the status information of signalingpoints belonging to each signaling network received from the signalingnetwork management unit 13, 23 of each signaling network processing unit10, 20.

[0059] As a result of the determination in step S270, if the destinationsignaling point of the signaling message is accessible, thecross-routing controlling unit 30 cross-routes the signaling message tothe corresponding signaling network. For example, if the destinationsignaling point of the signaling message is a signaling point D ofsignaling network y, the cross-routing controlling unit 30 cross-routesthe signaling message to the message routing unit 25c of the signalingmessage handling unit 25 in the signaling network y processing unit 20.The message routing unit 25 c then routes the received signaling messageto signaling network y by performing the message routing method as shownin FIG. 7.

[0060] As described above, the apparatus and method for interworkingbetween heterogeneous No. 7 signaling networks according to thepreferred embodiment of the present invention has many advantages. Forexample, the development of additional functions required forinterworking between heterogeneous No. 7 signaling networks can beminimized by operating the function of managing a signaling network andthe function of handling a signaling message, respectively, duringinterworking between different No. 7 signaling networks. In addition,the reliability and performance of a signaling network can be maximizedby using an already established function of managing each signalingnetwork.

[0061] The foregoing embodiments and advantages are merely exemplary andare not to be construed as limiting the present invention. The presentteaching can be readily applied to other types of apparatuses. Thedescription of the present invention is intended to be illustrative, andnot to limit the scope of the claims. Many alternatives, modifications,and variations will be apparent to those skilled in the art. In theclaims, means-plus-function clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents but also equivalent structures.

What is claimed is:
 1. An apparatus for interworking betweenheterogeneous No. 7 signaling networks, comprising: a plurality ofsignaling network processing units corresponding to heterogeneous No. 7signaling networks, each configured to interwork with each other in aone-to-one manner, and each configured to execute a signaling networkmanagement function and a signaling message handling function for acorresponding signaling network; and a cross-routing controlling unitcoupled between the plurality of signaling network processing units andconfigured to store network management information of each signalingnetwork transmitted from each of the plurality of signaling networkprocessing units and configured to cross-route a signaling messagebetween the plurality of signaling network processing units based on thestored network management information.
 2. The apparatus of claim 1,wherein each of the plurality of signaling network processing units eachcomprises: a signaling network management unit to perform networkmanagement for a corresponding signaling network and transmit a state ofeach signaling point corresponding to the signaling network to thecross-routing controlling unit; and a signaling message handling unit totransmit the signaling message to be cross-routed from a correspondingcurrent signaling network to the cross-routing controlling unit, androute the signaling message transmitted from the cross-routingcontrolling unit to a corresponding destination signaling network. 3.The apparatus of claim 2, wherein the signaling message handling unitcomprises: a message discrimination unit to determine whether thedestination signaling point of the signaling message is a currentsignaling point; a message distribution unit to distribute the signalingmessage to a corresponding local message transfer part (MTP) user partin the current signaling point, if the destination signaling point ofthe signaling message is the current signaling point; and a messagerouting unit to request that the signaling message be cross-routed to aheterogeneous signaling network, if the destination signaling point ofthe signaling message is not the current signaling point and does notexist in the corresponding current signaling network.
 4. The apparatusof claim 3, wherein the message routing unit routes the signalingmessage to the corresponding signaling network if it receives thesignaling message routed by the cross-routing unit, and if thedestination signaling point of the received signaling message iscontained in the corresponding signaling network and is accessible, andotherwise the message routing unit routes the signaling message to thecorresponding destination signaling point.
 5. The apparatus of claim 1,wherein the signaling network processing unit performs functions of amessage transfer part (MTP) protocol, and the cross-routing controllingunit performs functions of a MTP user part protocol for the signalingnetwork processing unit, among No. 7 protocols.
 6. The apparatus ofclaim 1, wherein the cross-routing controlling unit routes the signalingmessage to the signaling network processing unit of a destinationsignaling network in accordance with the status information of thesignaling point transmitted from each signaling network processing unit.7. A method of interworking between heterogeneous No. 7 signalingnetworks, comprising: receiving status information of signaling pointsfor each of a plurality of signaling networks from signaling networkprocessing units separated according to the type of a signaling networkto manage a status of the plurality of signaling networks; requestingcross-routing of a received signaling message to a heterogeneoussignaling network, if the destination signaling point of the signalingmessage is not contained in a homogeneous signaling network; andcross-routing the signaling message to a destination signaling networkif it is determined that cross-routing is possible based on the statusinformation of the destination signaling point.
 8. The method of claim7, wherein managing the status of the plurality of networks comprises:receiving a message transfer part (MTP) primitive representing thestatus information of a signaling point of a corresponding signalingnetwork; determining that the status of the signaling point of thecorresponding signaling network is accessible if the MTP primitive is aMTP-RESUME primitive representing that a signaling message can betransferred to a corresponding signaling point; determining that thestatus of the signaling point is inaccessible if the MTP primitive is aMTP-PAUSE primitive representing that a signaling message cannot betransferred to the corresponding signaling point; and determining thatthe status of the signaling point is congested if the MTP primitive is aMTP-STATUS primitive representing that congestion has occurred in thecorresponding signaling point.
 9. The method of claim 8, wherein the MTPprimitive is received from a signaling network management unit of asignal network processing unit.
 10. The method of claim 7, whereinrequesting cross-routing comprises: determining whether cross-routing ofthe signaling message to heterogeneous signaling networks is possible,if the destination signaling point of the signaling message receivedfrom the corresponding signaling network is not contained in anoriginating signaling network; transferring the signaling message to across-routing unit to perform cross-routing of the signaling messagebetween heterogeneous signaling networks, if the cross-routing of thesignaling message is possible; and removing the signaling message andprohibiting the transfer of the signaling message to the correspondingdestination signaling point, if the cross-routing of the signalingmessage is not possible.
 11. The method of claim 10, wherein thetransfer of the signaling message is carried out using a MTP-TRANSFERindication primitive.
 12. The method of claim 10, wherein determiningwhether cross-routing is possible comprises: storing information ofsignaling points of each signaling network capable of cross-routing asignaling message between heterogeneous signaling networks; determiningthat the cross-routing of the corresponding signaling message ispossible if the destination signaling point of the correspondingsignaling message corresponds to one of the stored signaling points; anddetermining that the cross-routing of the corresponding signalingmessage is not possible if the destination signaling point of thecorresponding signaling message does not correspond to one of the storedsignaling points.
 13. The method of claim 7, wherein the cross-routingcomprises: determining whether the destination signaling point of thesignaling message exists; determining whether the destination signalingpoint is accessible, if the destination signaling point exists; andcross-routing the signaling message to the signaling network processingunit of the signaling network to which the destination signaling pointbelongs if the destination signaling point is accessible.
 14. The methodof claim 13, wherein the determination of whether the destinationsignaling point is accessible is based on the status information of eachsignaling point received from each of the plurality of signalingnetworks.
 15. The method of claim 13, wherein the cross-routing stepfurther comprises removing the signaling message and prohibiting thetransfer of the signaling message to the corresponding destinationsignaling point if the destination signaling point or if the destinationsignaling point of the signaling message is not accessible.
 16. Themethod of claim 13, wherein the cross-routing of the signaling messageis carried out using a MTP-TRANSFER request primitive.
 17. A system forinterworking heterogeneous No. 7 signaling networks, comprising: firstand second signal network processing units, each coupled to acorresponding heterogeneous No. 7 signaling network; and a cross-routingcontrol unit coupled to each of the signal networking processing units,wherein the cross-routing control unit stores network managementinformation received from the first and second signal network processingunits and performs cross-routing of a signaling message from the firstsignal network processing unit to the second signal network processingunit.
 18. The system of claim 17, wherein the cross-routing control unitreceives a MTP-transfer primitive from the first signal networkprocessing unit, which indicates that a signaling message needs to betransferred from the first signaling network to the second signalingnetwork, determines whether a signaling point of the second signalingpoint is accessible, and cross-routes the signaling message from thefirst signaling network to the second signaling network if thedestination signaling point is accessible.
 19. The system of claim 17,wherein the cross-routing control unit receives a first MTP primitive,which represents status information of a first signaling point of thefirst signal network, receives a second MTP primitive, which representsstatus information of a second signaling point of the second signalingnetwork, determines a type the MTP primitive received from each of thefirst and second signaling points, and determines a status of each ofthe first and second singling points based on the type of MTP primitivereceived from the corresponding signaling point to manage the status ofeach of the signaling points.
 20. The system of claim 17, wherein eachof a first and second signaling point associated with the first andsecond network processing units, respectively, request crossrouting of asignaling message by determining if a destination signaling point existsin the requesting signaling network, determining whether cross-routingof the signaling message to the destination signaling network ispossible, and transmitting the signaling message to the cross-routingcontrol unit using a MTP-transfer indication primitive.
 21. The systemof claim 17, wherein each of the first and second signal networkprocessing units comprises: a signaling network management unit toperform network management for a corresponding signaling network andtransmit a state of each signaling point corresponding to the signalingnetwork to the cross-routing controlling unit; and a signaling messagehandling unit to transmit the signaling message to be cross-routed froma corresponding current signaling network to the cross-routingcontrolling unit, and route the signaling message transmitted from thecross-routing controlling unit to a corresponding destination signalingnetwork.
 22. The system of claim 21, wherein the signaling messagehandling unit comprises: a message discrimination unit to determinewhether the destination signaling point of the signaling message is acurrent signaling point; a message distribution unit to distribute thesignaling message to a corresponding local message transfer part (MTP)user part in the current signaling point, if the destination signalingpoint of the signaling message is the current signaling point; and amessage routing unit to request that the signaling message becross-routed to a heterogeneous signaling network, if the destinationsignaling point of the signaling message is not the current signalingpoint and does not exist in the corresponding current signaling network.23. The system of claim 22, wherein the message routing unit routes thesignaling message to the corresponding signaling network if it receivesthe signaling message routed by the cross-routing unit, and if thedestination signaling point of the received signaling message iscontained in the corresponding signaling network and is accessible, andotherwise the message routing unit routes the signaling message to thecorresponding destination signaling point.
 24. A method of managing astatus of signaling points for interworking between heterogeneous No. 7signaling networks, comprising: receiving a MTP primitive representingstatus information of a first signaling point; receiving a MTP primitiverepresenting status information of a second signaling point; determininga type of the MTP primitive received from each of the first and secondsignaling points; and determining a status of each of the first andsecond singling points based on the type of MTP primitive received fromthe corresponding signaling point.
 25. The method of claim 24, whereinthe type of the MTP primitive is one of MTP-RESUME, MTP-PAUSE, andMTP-CONGESTION, and wherein MTP-RESUME indicates that a signalingmessage can be transferred to the corresponding signaling point,MTP-PAUSE indicates that the signaling message cannot be transferred tothe corresponding signaling point, and MTP-CONGESTION indicates that thecorresponding signaling point is congested.
 26. A method of requestingcross-routing of a signaling message between heterogeneous No. 7signaling networks, comprising: receiving a signaling message for adestination signaling point from a first signaling network; determiningif the destination signaling point exists in the first signalingnetwork; determining whether cross-routing of the signaling message to asecond signaling network is possible if the destination signaling pointdoes not exist in the first network; and transmitting the signalingmessage to a cross-routing controller using the MTP-transfer indicationprimitive if cross-routing is possible.
 27. The method of claim 26,wherein the destination signaling point exists in the first signalingnetwork, then cross-routing is not performed, and it is determinedwhether the destination signaling point is accessible, and the signalingmessage is routed to the corresponding signaling network.
 28. The methodof claim 26, wherein if cross-routing is not possible, then thesignaling message is discarded and transfer of the signaling message isprohibited.
 29. The method of claim 26, wherein the cross-routingcontroller, upon receiving the MTP-transfer indication primitive,determines whether the destination signaling point exists, determineswhether the destination signaling point is accessible if the destinationsignaling point exists, and cross-routes the signaling message from thefirst signaling network to the destination signaling point if thedestination signaling point is accessible.
 30. A method cross-routing asignaling message between signaling points in a heterogeneous No. 7signaling network, comprising: receiving a MTP-transfer primitive from afirst signaling point indicating that a signaling message needs to betransferred from the first signaling point to a destination signalingpoint; determining whether the destination signaling point exists;determining whether the destination signaling point is accessible if thedestination signaling point exists; and cross-routing the signalingmessage from the first signaling point to the destination signalingpoint if the destination signaling point is accessible.
 31. The methodof claim 30, wherein the signaling message is discarded and the transferof the signaling message is prohibited if the destination signalingpoint does not exist or if the destination signaling point is notaccessible.
 32. The method of claim 30, further comprising receiving aMTP primitive representing status information of the first signalingpoint; receiving a MTP primitive representing status information of thedestination signaling point; and determining an accessibility status ofthe first signaling point and the destination signaling point based on atype of the received MTP primitive received from the correspondingsignaling point.